Method of inhibiting platelet aggregation

ABSTRACT

A class of 2-substituted benzisothiazolones carrying a nitrogen-containing heterocyclic ring are effective in inhibiting platelet aggregation and are therefore of value in the prophylactic and therapeutic treatment of thrombotic diseases.

This is a continuation of Ser. No. 850,788 filed Nov. 11, 1977 and nowabandoned, which was a divisional of Ser. No. 738,000, filed Nov. 2,1976, now U.S. Pat. No. 4,113,728, issued Sept. 12, 1978.

This invention relates to a class of benzisothiazolones which are ofvalue in the prophylactic and therapeutic treatment of thromboticdiseases. The invention also relates to a method for the preparation ofsuch compounds and to pharmaceutical compositions comprising them.

Arterial thrombosis develops initially from the aggregation of bloodplatelets within the artery. This aggregate may eventually lead to theformation of fibrin and the formation of a consolidated occlusivethrombus. The most widely used therapy for thrombosis is the use ofanti-coagulant agents, which influence blood clotting. However, althougheffective in venous thrombosis, where the thrombus is formed mainly offibrin, anti-coagulant therapy has no effect on platelet aggregation andhas therefore limited effectiveness in arterial thrombosis. It is nowaccepted that anti-coagulant drugs have little to offer in the treatmentof arterial thrombosis.

With the increasing recognition of the primary role of platelets inthrombosis, attention had turned to drugs which are capable ofinhibiting the aggregation of platelets.

It has now been found that a class of benzisothiazolones are effectivein inhibiting platelet aggregation.

Accordingly the present invention provides a compound of formula (I) ora pharmaceutically acceptable non-toxic acid addition salt thereof whenthere is a basic nitrogen atom in the molecule: ##STR1## wherein R¹ andR² are the same or different and each is hydrogen, lower alkyl, loweralkoxy, halo-lower alkyl, nitro, amino, acylamino, or halogen, or R¹together with R² when attached to adjacent carbon atoms represent a C₃-C₆ alkylene or oxy(C₁ -C₃)alkyleneoxy moiety; X represents a bond or astraight or branched chain alkylene group having from one to twelvecarbon atoms; and R represents a nitrogen-containing heterocyclic ring,or a group of formula --NH.R³ wherein R³ is a nitrogen-containingheterocyclic ring, the groups R and R³ being optionally substituted witha lower alkyl, carboxy or alkoxycarbonyl group; provided that,

(a) when X represents a bond, R is not a pyridmidyl, pyridyl orthiazolinyl or benzthiazolyl group; and

(b) when R¹ and R² are at positions 5 and 7 and are hydrogen or halogenand X is a lower alkylene group, then R is not a piperidinyl,pyrrolidinyl, morpholinyl or piperazinyl group which is attached via anitrogen atom thereof to the group X.

Suitable acid addition salts include inorganic salts such as thesulphate, nitrate, phosphate, and borate, hydrohalides e.g.hydrochloride, hydrobromide, and hydroiodide, and organic acid additionsalts such as acetate, oxalate, tartrate, maleate, citrate, succinate,benzoate, ascorbate, methanesulphonate and p-toluenesulphonate.

Suitable groups for the substituents R¹ and R² include methyl, ethyl, n-and iso-propyl, n-, sec-, iso, and tert-butyl, methoxy, ethoxy, n- andiso-propoxy, n-, sec-, iso- and tert-butoxy, chloro, bromo fluoro, tfluoromethyl. Preferably R¹ is hydrogen or a methyl group or chlorineatom. When neither R¹ nor R² are hydrogen, they are preferably loweralkyl or lower alkoxy, especially methyl or methoxy.

Preferably, R¹ and R² are at positions 5 and 6 respectively. In onesuitable class of compounds, the substituent at position 5 is a loweralkyl.

Suitable alkylene groups for the group X include, for example,methylene, ethylene, propylene, n-butylene, n-pentylene, n-hexylene,n-dodecylene, 1-methylethylene, 1- or 2-methylpropylene, isopropylene,isobutylene. Preferably, the group X has from 1 to 6 carbon atoms,especially two carbon atoms.

When either group R or R³ is a nitrogen-containing heterocyclic ring,such a ring may be aromatic or non-aromatic, and the attachment to thegroup X (in the case of group R) or the group NH (in the case of group^(R) 3) may be via, for example, the nitrogen atom or a carbon atom. Thering may also contain other hetero atoms, for example oxygen or sulphur.The group R or ^(R) 3 may represent single or polycyclic rings and maycomprise a total of from 5 to 12 atoms. Examples of such rings includepyrimidyl, 2-, 3- or 4-pyridyl, pyrrolyl, thiazolyl, thiazolinyl,diazolyl, triazolyl, tetrazolyl, thiatriazolyl, oxazolyl, oxadiazolyl,purinyl, tetrahydroquinolyl, tetrahydroisoquinolyl, benzimidazolyl,benzoxazolyl, benzthiazolyl, benzisothiazolonyl, piperidinyl,pyrrolidinyl, morpholinyl, piperazinyl, 3-azabicyclo [3.2.2] non-3-yl,9-azabicyclo [3.3.1] non-9-yl, homopiperidinyl, 2-azabicyclo [2.2.2]non-2-yl. Suitably R or R³ represents 2-pyridyl, 1-pyrrolidinyl,1-piperidinyl, 1-homopiperidinyl 2-methylpiperidin-1-yl, 3-azabicyclo[3.2.2] non-3-yl, tetrahydroisoquinolyl.

The group R or R³ may be optionally substituted with a lower alkyl,carboxy or alkoxycarbonyl group. Preferred alkoxycarbonyl groups areC₁₋₆ alkoxycarbonyl groups for example methoxycarbonyl, ethoxycarbonyl,n- and iso-propoxycarbonyl, n-, iso-, sec- and tert-butoxycarbonyl.Preferred lower alkyl groups include methyl and ethyl, especiallymethyl.

From the foregoing it may be seen that one suitable class of compoundsaccording to this invention are compounds of formula (II) andpharmaceutically acceptable non-toxic acid addition salts thereof:##STR2## wherein R¹ and R² are as defined with respect to formula (I)above Y is a straight-or branched-alkylene chain having from one totwelve carbon atoms and R⁴ is a nitrogen-containing aromatic ring.Suitable groups R⁴ include pyrimidyl, pyridyl, thiazolyl. Specificcompounds of formula (II) include the following:

2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one;

2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one hydrochloride;

6-chloro-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one hydrochloride;

5-chloro-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one hydrochloride;

5-methyl-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one hydrochloride;

5,6-dimethyl-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one;

6-nitro-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one;

6-amino-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one;

6-acetylamino-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one;

5,6-dichloro-2-(3'-pyridylmethyl)-1,2-benzisothiazol-3-one;

2-b-(4-methyl-2-thiazolyl)ethyl-1,2-benzisothiazol-3-one;

5-methyl-2-β-(4-methyl-2-thiazolyl)ethyl-1,2-benzisothiazol-3-one.

Another sub-class of compounds within the present invention comprisescompounds of formula (III) and pharmaceutically acceptable non-toxicacid addition salts of such compounds having a basic nitrogen atom:##STR3## wherein R¹ and R² are as defined with respect to formula (I)above, and R⁵ is thiazolyl, piperidinyl, pyrrolidinyl, morpholinyl,piperazinyl, 3-azabicyclo[3.2.2]non-3-yl, 9-azabicyclo[3.3.1]non-9-yl,homopiperidinyl and 2-azabicyclo[2.2.2]non-2-yl.

Specific compounds of formula (III) include the following:

2-(morpholino)-1,2-benzisothiazol-3-one;

2-(thiazol-2-yl)-1,2-benzisothiazol-3-one;

A further class within this invention comprises compounds of formula(IV) and pharmaceutically acceptable non-toxic acid addition salts ofsuch compounds having a basic nitrogen: ##STR4## wherein R¹ and R² areas defined with respect to formula (I) above, Y is a straight-orbranched-alkylene chain having from one to twelve carbon atoms, and R⁶is 3-azabicyclo[3.2.2]non-3-yl, 9-azabicyclo[3.3.1]non-9-yl,homopiperidinyl and 2-azabicylo[2.2.2]non-2-yl, or1,2-benzisothiazol-3-on-2-yl, tetrahydroisoquinolyl. Specific compoundsof formula (IV) include the following:

2-β-(3-azabicyclo[3.2.2]non-3-yl)ethyl-1,2-benzisothiazol-3-onehydrochloride;

5,6-dichloro-2-β-(1-pyrrolidinyl)ethyl-1,2-benzisothiazol-3-one;

5,6-dichloro-2-β-(1-pyrrolidinyl)ethyl-1,2-benzisothiazol-3-onehydrochloride;

5,6-dichloro-2-β-(3-azabicyclo[3.2.2]non-3-yl)ethyl-1,2-benzisothiazol-3-one;

2-β-(homopiperidin-1-yl)ethyl-1,2-benzisothiazol-3-one hydrochloride;

1,2-bis(1,2-benzisothiazol-3-on-2-yl)ethane;

5,6-dimethoxy-2-β-(3-azabicyclo[3.2.2]non-3-yl)ethyl1,2-benzisothiazol-3-one;

5,6-dimethyl-2-β-(3-azabicyclo[3.2.2]non-3-yl)ethyl1,2-benzisothiazol-3-one;

2-β-(9-azabicyclo[3.3.1]non-9-yl)ethyl-1,2-benzisothiazol-3-one;

2-β-(N-tetrahydroisoquinolylethyl)-1,2-benzisothiazol-3-onehydrochloride.

Another group of compounds within the present invention have formula(V), and pharmaceutically acceptable acid addition salts of suchcompounds having a basic nitrogen atom: ##STR5## wherein R¹, R², R³ andX are as defined with respect to formula (I) above. Specific compoundsof formula (V) include the following:

2-[2'-pyridylaminomethyl]-1,2-benzisothiazol-3-one;

2-[4'-pyridylaminomethyl]-1,2-benzisothiazol-3-one;

2-[5'-ethoxycarbonylthiazol-2'-yl)aminomethyl]-1,2-benzisothiazol-3-one;

Other specific compounds falling within this invention include thefollowing:

5-methyl-2-(β-1-pyrrolidinylethyl)-1,2-benzisothiazol-3-one oxalate;

5,6-dimethyl-2-(β-1-pyrrolidinylethyl)-1,2-benzisothiazol-3-one;

2-[β-(2-methyl-1-pyrrolidinyl)ethyl]-1,2-benzisothiazol-3-one.

The compounds of this invention may be prepared by reacting a compoundof formula (VI): ##STR6## wherein R¹ and R² are as defined with respectto formula (I) above, and W and Z are the same or different and each isa halogen atom; with a compound of formula (VII):

    NH.sub.2.X.R                                               (VII)

wherein X and R are as defined with respect to formula (I) above.

Preferably W is chlorine and Z is chlorine or bromine. Suitable solventsfor the reaction include carbon tetrachloride or other halogenatedhydrocarbon solvents.

A second method for the preparation of the compounds of formula (I)comprises reaction of a compound of formula (VIII) or a salt thereof:##STR7## wherein R¹ and R² are as defined with respect to formula (I)above; and with a compound of formula (IX):

    Q--X--R                                                    (IX)

wherein X and R are as defined with respect to formula (I) above and Qis a readily displaceable group. Suitably, Q is a halogen atom.Preferably the compound (VIII) is used as its alkali metal salt, forexample the sodium salt.

In this reaction a solvent such as dimethyl formamide ordimethylsulphoxide may be used, preferably at elevated temperatures. Ingeneral the corresponding 3-ether is also formed and the desired productmay be separated by crystallisation, distillation and chromatographictechniques.

The intermediate (IX) may if desired be formed in situ in the reaction.For example, for compounds of formula (I) wherein X represents a CH₂group, this process may be operated by reacting compound (VIII) with anamine R.NH₂ in the presence of formaldehyde.

Compounds of formula (I) may also be prepared by treating a compound offormula (X): ##STR8## wherein R¹, R², X and R are as defined withrespect to formula (I) above; with either a base or with chlorine orbromine.

Suitable bases include 10% sodium hydroxide or other aqueous alkali andthe reaction may be carried out at room temperature or elevatedtemperatures. If chlorine is employed in this reaction it may be bubbledinto a solution of compound (X) in an inert solvent such as carbontetrachloride.

Compounds of formula (I) may also be prepared by treating a compound offormul (XI): ##STR9## wherein X, R, R¹ and R² are as defined withrespect to formula (I) above and CO₂ R_(a) is a carboxylic ester group;with a base.

Suitably the group R_(a) is an alkyl or aryl group. Suitable bases forthe reaction include alkali metal alkoxides, alkali metal hydroxides andtetramethylammonium hydroxide in lower alcohols.

The compounds of formula (I) wherein X represents a bond may be preparedby a process which comprises reacting a compound of formula (XII):##STR10## wherein R¹ and R² are as defined with respect to formula (I)above; with an amine R.NH₂ wherein R is as defined with respect toformula (I) above.

This reaction may conveniently be carried out in a lower alcohol atelevated temperatures.

Compounds of formula (I) wherein R represents a nitrogen-containingheterocyclic ring attached to the group X via the ring nitrogen, or agroup --NH.R³ may be prepared by reacting a compound of formula (XIII):##STR11## wherein R₁, R² and X are as defined with respect to formula(I) above and U represents a readily displaceable group; with a compoundof formula (XIVA) or (XIVB); ##STR12##

R³ is as defined with reference to formula (I) above, and Z is theresidue of a heterocyclic ring.

Suitably the group U is a halogen atom, for example chlorine or bromine;a substituted sulphonyloxy group, for example p-toluenesulphonyloxy ormethanesulphonyloxy.

The reaction may suitably be carried out in a hydrocarbon solvent suchas toluene at an elevated temperature for example 100°-120°.

The invention also provides a pharmaceutical composition which comprisesa compound of formula (I) as defined above together with at least onepharmaceutically acceptable carrier.

As is common practice, such compositions will usually be accompanied byor associated with written or printed directions for use in the medicaltreatment concerned, in this case as an agent for the inhibition ofplatelet aggregation or thrombus formation.

The compositions may be formulated for administration by any route,although an oral administration is preferred. The compositions may be inthe form of tablets, capsules, powders, granules, lozenges, or liquidpreparations, such as oral or sterile parenteral solutions orsuspensions.

Tablets and capsules for oral administration may be in unit dosepresentation form, and may contain conventional excipients such asbinding agents, for example syrup, acacia, gelatin, sorbitol,tragacanth, or polyvinyl-pyrollidone; fillers, for example lactose,sugar, maize-starch, calcium phosphate, sorbitol or glycine; tablettinglubricants, for example magnesium stearate, talc, polyethylene glycol,or silica; disintegrants, for example potato starch; or acceptablewetting agents such as sodium lauryl sulphate. The tablets may be coatedaccording to methods well known in normal pharmaceutical practice. Oralliquid preparations may be in the form of, for example, aqueous or oilysuspensions, solutions, emulsions, syrups, or elixirs, or may bepresented as a dry product for reconstitution with water or othersuitable vehicle before use. Such liquid preparations may containconventional additives such as suspending agents, for example sorbitol,syrup, methyl cellulose, glucose syrup, gelatin, hydroxyethylcellulose,carboxymethyl cellulose, aluminium stearate gel or hydrogenated ediblefats, emulsifying agents, for example lecithin, sorbitan monooleate, oracacia; nonaqueous vehicles (which may include edible oils), for examplealmond oil, fractionated coconut oil, oily esters such as glycerine,porpylene glycol, or ethyl alcohol; preservatives, for example methyl orpropyl p-hydroxybenzoate or sorbic acid, and if desired conventionalflavouring or colouring agents. The compound may also if desired byincorporated in a foodstuff, for example in the form of a biscuit.

For parenteral administration, fluid unit dosage forms are preparedutilizing the compound and a sterile vehicle, water being preferred. Thecompound, depending on the vehicle and concentration used, can be eithersuspended or dissolved in the vehicle. In preparing solutions thecompound can be dissolved in water for injection and filter sterilizedbefore filling into a suitable vial or ampoule and sealing.Advantageously, adjuvants such as a local anesthetic, preservative andbuffering agents can be dissolved in the vehicle. To enhance thestability, the composition can be frozen after filling into the vial andthe water removed under vacuum. The dry lyophilized powder is thensealed in the vial and an accompanying vial of water for injection issupplied to reconstitute the liquid prior to use. Parenteral suspensionsare prepared in substantially the same manner except that the compoundis suspended in the vehicle instead of being dissolved and sterilizationcannot be accomplished by filtration. The compound can be sterilized byexposure to ethylene oxide before suspending in the sterile vehicle.Advantageously, a surfactant or wetting agent is included in thecomposition to facilitate uniform distribution of the compound.

The compositions may contain from 0.1% to 99% by weight, preferably from10-60% by weight, of the active material, depending on the method ofadministration. Where the compositions comprise dosage units, each unitwill preferably contain from 1-500 mg., of the active ingredient.

The dosage employed for adult treatment will of course depend on thedose-response characteristics of the particular active ingredient, andalso on the blood volume and condition of the patient, but will normallybe in the range 0.01 to 30 mg/kg/day depending on the route andfrequency of administration. The preferred dose is 10 to 500 mg., orally1 to 3 times a day for an adult human.

The compositions of the invention are useful for administration tohumans and animals to prevent clot formation for example after surgeryto prevent postoperative thrombosis; in geriatric patients to preventtransient cerebral ischemic attacks; and long-term prophylaxis followingmyocardial infarcts and strokes.

The compounds of formula (I) may also have applications in the storageof whole blood in blood banks, and whole blood to be used in heart-lungmachines, or to be circulated through organs, e.g. heart and kidneys,which have been removed from a cadaver and prior to transplant.

Accordingly, this invention also provides a process for inhibitingplatelet aggregation in vitro comprising the addition of a compound ofthe formula (XV) or a pharmacologically acceptable acid addition salt ofsuch a compound having a basic nitrogen atom in the molecule: ##STR13##wherein R¹ and R² are the same or different and each is hydrogen, alower alkyl, lower alkoxy, halo-lower alkyl, nitro, amino, acylamino orhalogen, or R¹ together with R² when attached to adjacent carbon atomsrepresent a C₃ -C₆ alkylene or oxy(C₁ -C₃)alkyleneoxy moiety;

X represents a bond or a straight or branched chain alkylene grouphaving from one to twelve carbon atoms; and

R represents a nitrogen-containing heterocyclic ring, or a group offormula --NH.R³ wherein R³ is a nitrogen-containing heterocyclic ringthe groups R and R³ being optionally substituted with a lower alkyl,carboxy or alkoxycarbonyl group; to whole blood or platelet-richconcentrates.

The dosage for such an addition is preferably from 0.01 to 50micrograms/ml of whole blood.

The invention also provides a composition comprising whole blood and acompound of formula (XV) above or a pharmacologically acceptable acidaddition salt of such a compound having a basic nitrogen atom in themolecule.

The following Examples illustrate the preparation of some of thecompounds of this invention.

EXAMPLE 1 5-Chloro-2[β-(2-pyridyl)ethyl]-1,2-benzisothiazol-3-onehydrochloride ##STR14##

To a suspension of 5,5'-dichloro-2,2'-dithiodibenzoylchloride (4.12 g.0.01 mole) in dry CCl₄ (100 ml), chlorine was passed until solution wascomplete (approx. 11/2 hours) and excess chlorine removed by passingnitrogen through the solution. The solution was then filtered and addedto a solution of 2-(2-aminoethyl)pyridine (7.32 g, 0.05 M) in dry CCl₄(100 ml) in a three necked 500 ml. round bottomed flask fitted with adrying tube and stirred. After the addition was complete (about 1/2hour), the solution was stirred at room temperature for a further hour.The reaction mixture was washed with water and then extracted with 2 NHCl solution. The acid extract was basified with 2 N sodium hydroxidesolution and extracted with dichloromethane. The organic extract wasdried over Mg SO₄, filtered and the solvent evaporated to yield thecrude free base. This was dissolved in isopropyl alcohol and hydrogenchloride was passed into the solution to form the salt. After removal ofisopropanol under reduced pressure the resulting hydrochloride salt wasrecrystallised from ethanol. (3.5 g. 68%) Mpt. 178°-81° C.

EXAMPLE 22-[6-(3-azabicyclo[3.2.2]non-3-yl)-hexyl]-1,2-benzisothiazlol-3-onehydrochloride ##STR15##

Chlorine was passed into a suspension of 2,2'-dithiodibenzoyl chloride(6.8 g. 0.01 mole) (1) in dry CCl₄ (100 ml) until solution was completethen excess chlorine removed in a stream of nitrogen. The solution wasthen filtered and added slowly with stirring to a solution of6-amino-hexanol (7.02 g, 0.06 mole) in dry CCl₄ (100 ml) at 0° C. Afterthe addition was complete (30 minutes), the mixture was stirred at roomtemperature for a further hour then washed with water. The organicsolution was dried (anhyd. Mg SO₄) and filtration and removal of thesolvent under reduced pressure yielded 3 as an un-crystallisable gum,pure by thin layer chromatography (4.8 g. 92%). The infra-red and protonmagnetic resonance spectra was consistant with the proposed structure.##STR16##

To a solution of 2-(6-hydroxyhexyl)-1,2-benzisothiazol-3-one (5 g. 0.02mole) (30 in pyridine (30 ml) at 0° C. p-toluenesulphonyl chloride (7.6g) was added (4) maintaining the temperature of the reaction mixture at0° with external cooling. The reaction mixture was allowed to stand atroom temperature for 12 hours and was then poured into ice/water. Theproduct 5 was isolated by extraction with dichloromethane in the usualmanner. The crude product was taken up in ethanol treated with activatedcarbon and filtered through celite. Evaporation of the ethanol yieldedpure 5 as an un-crystallizable gum pure by thin layer chromatographyinfra-red and proton magnetic spectra. Yield 7.2 g. 90%. ##STR17##

A solution of the tosylate 5 (4.05 g. 0.01 mole) and3-azabicyclo[3.2.2]nonone (1.25 g. 0.01 mole) in toluene (100 ml) wereheated under reflux for 5 hours then cooled. The mixture was thenextracted with 10% HCl solution and the acid extract basified with 10%sodium hydroxide solution. The crude of 6 was isolated by extractionwith dichloromethane in the usual manner. The hydrochloride salt wasprepared by dissolving the crude base in isopropyl alcohol and passinghydrogen chloride gas into the solution. Removal of the solvent yieldeda gum which solidified on trituration with acetone. Recrystallisation ofthe solid from ethanol yielded pure 6 (3.4 g. 72%) m.p. 167°-9°.

EXAMPLE 3 5,6-Dimethoxy-2[β-(2-pyridyl)ethyl]-1,2-benzisothiazol-3-one##STR18##

To a suspension of 4,4',5,5'-tetramethoxy-2,2'-dithiodibenzoylchloride(2.0 g, 4.32 mmole) in dry ether (100 ml) containing pyridine (4 ml) wasadded 2-(2-aminoethyl)pyridine (1.60 g. 13.0 mmole) in dry ether (50 ml)dropwise with stirring at room temperature. The mixture was stirred for1 hour and allowed to stand for 18 hours before the solvent wasevaporated under reduced pressure. A solution of the residue indichloromethane was washed with water and then shaken with 2 Nhydrochloric acid. The acid layer was basified with 10% aqueous sodiumhydroxide solution and the mixture was extracted twice withdichloromethane. The organic extracts were combined and dried overmagnesium sulphate. Removal of the solvent gave a yellow solid which wasrecrystallised from isopropanol yielding the product 6 as cream colouredneedles (1.18 g, 43%) m.p. 154.5°-156.5°.

EXAMPLE 4 2-[2'-Pyridylaminomethyl]-1,2-benzisothiazol-3-one ##STR19##

To a solution of 1,2-benzisothiazol-3-one (9) (1.5 g., 0.01 mole) and2-aminopyridine (1 g., 0.0106 mole) in ethanol (20 ml) formalin solution(2 ml) was added and the mixture allowed to stand at room temperaturefor three days. After removal of the solvent under reduced pressure theresidue was taken up in ether and washed with water. The ether layer wasdried (Mf 50₄) and after removal of the ether the crude product wascrystallised from EtOH to yield pure 10 (0.55 g., 27%) m.p. 168-170 dec.

EXAMPLES 5-8

The following compounds were prepared using the method as described inExample 1:

    ______________________________________                                         ##STR20##                                                                    Example                                                                       No.     R.sup.1                                                                             R.sup.2                                                                              R.sup.5   m.p. (°C.)                                                                     yield (%)                              ______________________________________                                        5.      H     H      morpholinyl                                                                             122-3°                                                                         60                                     6.      Cl    H      2-pyridyl 239°                                                                           55                                                                    -239.5°                                 7.      Cl    H      2-pyrimidinyl                                                                           275-9°                                                                         31                                     8.      H     H      thiazol-2-yl                                                                            240.2°                                                                         32                                     ______________________________________                                    

EXAMPLES 9-21

The following compounds were prepared using the method shown:

    __________________________________________________________________________     ##STR21##                                                                                                             Prepared by                          Example                                  method of                            No.  R.sup.1                                                                            R.sup.2                                                                            R           m.p. (°C.)                                                                     Yield (%)                                                                           Example No.                          __________________________________________________________________________     9.  H    H    2-pyridyl.HCl.                                                                            183-5°                                                                         62    1.                                   10.  CH.sub.3                                                                           H    2-pyridyl.HCl.                                                                            176-8°                                                                         65    1.                                   11.  H    Cl   2-pyridyl.HCl.                                                                            172-3°                                                                         58    1.                                   12.  Cl   Cl   2-pyridyl   167.5-70°                                                                      35    3.                                   13.  H    H    3-azabicyclo[3.2.2]-                                                                      238-245° (Dec)                                                                 80    2.                                                  non-3-yl.HCl.                                                  14.  Cl   Cl   3-azabicyclo[3.2.2]-                                                                      160-2°                                                                         60.5  2.                                                  non-3-yl                                                       15.  CH.sub.3 O                                                                         CH.sub.3 O                                                                         3-azabicyclo[3.2.2]-                                                                      229-32°                                                                        63    3.                                                  non-3-yl.HCl.                                                  16.  Cl   Cl   1-pyrrolidinyl                                                                            152.5-154.5°                                                                   38    1.                                   17.  Cl   Cl   1-pyrrolidinyl HCl                                                                        243-5° (Dec)                                                                   17    1.                                   18.  CH.sub.3 O                                                                         CH.sub.3 O                                                                         1-pyrrolidinyl HCl                                                                        223-5°                                                                         39    3.                                   19.  H    H    1-homopiperidinyl HCl.                                                                    178-80°                                                                        55    2.                                   20.  H    H    N4 1,2,3,4-tetrahydro-                                                                    180-95° (Dec)                                                                  60    2.                                                  isoquinolyl.HCl.                                               21.  H    H    1,2-benzisothiazol-                                                                       210-11°                                                                        50                                                        3-on-2-yl                                                      __________________________________________________________________________

EXAMPLES 22-23

The following compounds were prepared using the method as described inExample 4:

    ______________________________________                                         ##STR22##                                                                    Example                                                                       No.    R.sub.3            m.p. (°C.)                                                                       yield (%)                                 ______________________________________                                        22.    (4-ethoxycarbonyl)thiazol-2-yl                                                                   234-6°                                                                           39                                        23.    4-pyridyl          218-9°                                                                           28                                        ______________________________________                                    

EXAMPLES 24-25

The following compounds were prepared using the method as described inExample 1:

    ______________________________________                                         ##STR23##                                                                    Example                               m.p. Yield                              No.    R.sup.1                                                                              R.sup.2                                                                             X        R        (°C.)                                                                       (%)                                ______________________________________                                        24.    Cl     Cl    CH.sub.2 3-pyridyl                                                                              208°                                                                        25                                 25.    CH.sub.3                                                                             H     (CH.sub.2).sub.2                                                                       1-pyrrolidinyl                                                                         165°                                                                        53                                                              (oxalate salt)                                   ______________________________________                                    

EXAMPLES 26-27

The following compounds were prepared using the method as described inExample 2:

    ______________________________________                                         ##STR24##                                                                    Example No.                                                                            R               m.p. (°C.)                                                                       Yield (%)                                  ______________________________________                                        26       tetrahydroquinolyl                                                                            180-195   50                                                  (hydrochloride)1/2H.sub.2 O.                                                                  (dec)                                                27       2-methylpiperidinyl                                                                           223-5     43                                                  (hydrochloride)                                                      ______________________________________                                    

EXAMPLE 28

5,6-Dimethyl-1-(β-1-pyrrolidinylethyl)-1,2-benzisothiazol-3-one wasprepared using the method as described in Example 3, melting point105°-107° C.

EXAMPLE 29 Preparation of2-β-(4-methyl-2-thiazolyl)ethyl-1,2-benzisothiazol-3-one

To a stirred suspension ofN,N'-bis-[2-(4-methyl-2-thiazolyl)ethyl]-2,2'-dithio-bis-benzamide (3.1g., 5.6 mmole) in carbon tetrachloride (50 ml) a solution of bromine(0.89 g., 5.6 mmole) in carbon tetrachloride (10 ml) was added in oneportion. The mixture was stirred at room temperature for 10 minutes. Theresulting o-bromothiol-N-[2-(4-methyl-2-thiazolyl)ethyl]-benzamide wasfiltered off, washed with carbon tetrachloride then suspended in glacialacetic acid (30 ml) and heated under reflux for 20 minutes. The reactionmixture was cooled, the acetic acid removed under vacuume and theresidue basified with 10% aqueous sodium hydroxide solution. The mixturewas diluted with water (50 ml), extracted with dichloromethane (2×50 ml)and the organic phase dried (anhyd. MgSO₄). Removal of the drying agentand solvent yielded a gum (3 g) which after chromatography on aluminawith dichloromethane as eluant, yielded pure2-β-(4-methyl-2-thiazolyl)ethyl-1,2-benzisothiazol-3-one, 2.1 g., m.p.82°-83°, yield 68%.

EXAMPLE 30

2-β-(4-Methyl-2-thiazolyl)ethyl-5-methyl-1,2-benzisothiazol-3-one wasprepared in a similar manner to that described in Example 29. m.p.129-130. Yield 42%.

EXAMPLE 31 Preparation of5-methyl-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one ##STR25##

To a stirred suspension of dimethyl 2,2'-dithio-5,5'-dimethyldibenzoate(5 g., 4 mmole) in carbon tetrachloride (35 ml) at room temperature, asolution of bromine (2.21 g., 14 mmole) in the same solvent (20 ml) wasadded over 15 minutes. The mixture was stirred at room temperature for afurther 30 minutes, then added dropwise to a solution of2-(2-aminoethyl) pyridine (3.52 g., 29 mmole) and triethylamine (2.93g., 29 mmole) in carbon tetrachloride (35 ml) over 15 minutes. Stirringwas continued for a further 30 minutes, then the mixture was heatedunder reflux for 1 hour. The reaction mixture was cooled, diluted withchloroform (100 ml), and washed well with water (2×100 ml). The organiclayer was dried (anhyd. MgSO₄). Removal of the solvent yieldN-(β-2'-pyridylethyl)-2-methoxycarbonyl-4-methylbenzenesulphenamide asan oil (9.45 g).

This crude material in ethanol (40 ml) was treated with a solution ofsodium hydroxide (0.12 g) in ethanol (10 ml) and the mixture heatedunder reflux for 2 hours. The ethanol was removed under reduced pressureand the residue partitioned between water (100 ml) and chloroform (50ml). The organic layer was washed with water (100 ml), dried, (anhyd.MgSO₄) and the solvent removed under reduced pressure. The residue waspurified by chromatography on alumina using dichloromethane as eluantyielding 5-methyl-2-(β-2'-pyridylethyl)-1,2-benzisothiazol-3-one (5.0g., 67%), m.p. 103°-105° C. (aq. EtOH).

BIOLOGICAL DATA

The compounds of the Examples above were tested for their ability toinhibit platelet aggregation in vitro as follows:

Human blood (20 ml) is drawn into a plastic syringe and immediatelyanti-coagulated by mixing with 0.1 volumes of 3.8% (w/v) trisodiumcitrate dihydrate. Platelet-rich-plasma (PRP) is prepared bycentrifuging the anti-coagulated blood at 180 g., for 12 minutes, atroom temperature. Collagen (3×-bovine achilles tendon) is suspended in0.9% (w/v) saline, using a commercially available mixer emulsifier. PRPwas mixed with 0.1 volumes saline (control) or compound dissolved insaline and incubated at 37° for 3 minutes, before the addition ofcollagen. Water-insoluble compounds were added to PRP, dissolved in0.005 volumes dimethylformamide, the solvent being included in controlswhen appropriate. The final concentration of each compound was 100 μM.

Platelet aggregation in response to collagen was measuredphotometrically (Born, G. V. R., 1962, Nature, 194, 927) in a Brystonaggregometer coupled to a Vitatron linear pen recorder. The activity ofeach compound was expressed as percentage inhibition of the aggregationresponse to a dose of collagen producing a just-maximal change in lighttransmission in control PRP.

The results are shown in Table I.

                  TABLE 1                                                         ______________________________________                                        Compound of           Compound of                                             Example No.                                                                            % Inhibition Example No.                                                                              % Inhibition                                 ______________________________________                                        1        100          14         100                                          2        100          15          92                                          3        100          16         100                                          4        100          17         100                                          5        100          18          91                                          6        100          19          92                                          7        100          20         100                                          8        100          21          91                                          9        100          22         100                                          10       100          23          23                                          11       100          26         100                                          12       100          27         100                                          13       100          31         100                                          ______________________________________                                    

I claim:
 1. A method of inhibiting platelet aggregation in humans andanimals, of inhibiting thromboses in humans and animals and for treatingarterial thromboses in humans and animals which comprises administeringto a human or animal in need thereof, in an amount sufficient to inhibitplatelet aggregation, an amount sufficient to inhibit the formation ofthrombs or an amount sufficient to dissolve thromboses, a compound ofthe formula ##STR26## or a pharmaceutically acceptable non-toxic acidaddition salt thereof when there is a basic nitrogen atom in themolecule, wherein R¹ and R² are the same or different and each ishydrogen, lower alkyl, lower alkoxy, halo-lower alkyl, nitro, amino,acetylamino or halogen; or R¹ together with R² when attached to adjacentcarbon atoms form an alkylene moiety of 3 to 6 carbon atoms or anoxyalkyleneoxy moiety of 1 to 3 carbon atoms; X is a bond or a straightor branched chain alkylene of 1 to 12 carbon atoms; and R ispyrrolidinyl, unsubstituted or substituted by one lower alkyl, carboxyor alkoxycarbonyl of 1 to 6 carbon atoms in the alkoxyl moiety, or agroup of the formula--NH.R³ wherein R³ is pyrrolidinyl, unsubstituted byone lower alkyl, carboxy or alkoxycarbonyl of 1 to 6 carbon atoms in thealkoxyl moiety, provided that R¹ and R² are not hydrogen or lower alkylwhen X is alkylene of two carbon atoms and R is unsubstitutedpyrrolidinyl.
 2. A method according to claim 1 wherein R¹ and R² are thesame or different and each is lower alkoxy, halo-lower alkyl or halogen.3. A method according to claim 1, wherein R¹ and R² are the same ordifferent and each is lower alkoxy or halogen.
 4. A method according toclaim 3, wherein R¹ and R² are in the 5- and 6- positions.
 5. A methodaccording to claim 1, wherein the compound is in the form of an acidaddition salt selected from the group consisting of a sulphate, nitrate,phosphate, borate, hydrochloride, hydrobromide, hydroiodide, acetate,oxalate, tartrate, maleate, citrate, succinate, benzoate, ascorbate,methane sulphonate and p-toluene sulphonate.
 6. A method according toclaim 1, wherein X is methylene, ethylene, propylene, n-butylene,n-pentylene, n-hexylene, n-dodecylene, 1-methylethylene, 1- or2-methylpropylene, isopropylene or isobutylene.
 7. A method according toclaim 1, wherein X is straight or branch chain alkylene of 1 to 6 carbonatoms.
 8. A method according to claim 1, wherein X is alkylene of 2carbon atoms.
 9. A method according to claim 1, wherein R¹ and R² arethe same or different and each is methoxy, ethoxy, n-propoxy,iso-propoxy, n-butoxy, sec-butoxy, iso-butoxy, tert-butoxy, chloro,bromo, fluoro, or trifluormethyl.
 10. A method according to claim 1,wherein R¹ is chloro.
 11. A method according to claim 1, wherein R¹ andR² are the same or different and each is methoxy, or chloro.
 12. Amethod according to claim 1, wherein the compound is of the formula##STR27## or a pharmaceutically acceptable non-toxic acid addition saltthereof when there is a basic nitrogen atom in the molecule wherein R¹and R² are the same or different and each is hydrogen, lower alkyl,lower alkoxy, halo-lower alkyl, nitro, amino, acetylamino or halogen; orR¹ together with R² when attached to adjacent carbon atoms form analkylene moiety of 3 to 6 carbon atoms or an oxyalkyleneoxy moiety of 1to 3 carbon atoms; and R⁵ is pyrrolidinyl, unsubstituted or substitutedby one lower alkyl, carboxy or alkoxycarbonyl of 1 to 6 carbon atoms inthe alkoxyl moiety provided that R¹ and R² are not hydrogen or loweralkyl when x is alkylene of two carbon atoms and R is unsubstitutedpyrrolidinyl.
 13. A method according to claim 1, wherein the compound isof the formula ##STR28## or a pharmaceutically acceptable non-toxic acidaddition salt thereof when there is a basic nitrogen atom in themolecule, wherein R¹ and R² are the same or different and each ishydrogen, lower alkyl, lower alkoxy, halo-lower alkyl, nitro, amino,acetylamino or halogen; or R¹ together with R² when attached to adjacentcarbon atoms form an alkylene moiety of 3 to 6 carbon atoms or anoxylkyleneoxy moiety of 1 to 3 carbon atoms; X is a bond or a straightor branched chain alkylene of 1 to 12 carbon atoms; and R³ ispyrrolidinyl, unsubstituted or substituted by one lower alkyl, carboxyor alkoxycarbonyl of 1 to 6 carbon atoms in the alkoxyl moiety.
 14. Themethod according to claim 1, wherein R and R³ is 1-pyrrolidino.
 15. Themethod according to claim 14, wherein said compound is5,6-dichloro-2-[β-(1-pyrrolidinyl)ethyl]-1,2-benzisothiazol-3-one. 16.The method according to claim 14, wherein said compound is5,6-dichloro-2-[β-(1-pyrrolidinyl)ethyl]-1,2-benzisothiazol-3-onehydrochloride.
 17. The method according to claim 14, wherein saidcompound is5,6-dimethoxy-2-[β-(1-pyrrolidinyl)ethyl]-1,2-benzisothiazol-3-one. 18.The method for inhibiting platelet aggregation in vitro which comprisesadding a compound of the formula ##STR29## or a pharmaceuticallyacceptable acid addition salt thereof when there is a basic nitrogenatom in the molecule wherein R¹ and R² are the same or different andeach is hydrogen, lower alkyl, lower alkoxy, halo-lower alkyl, nitrogen,amino, acetylamino or halogen; or R¹ and R² when attached to adjacentcarbon atoms form an alkylene moiety of 3 to 6 carbon atoms or anoxy-alkyleneoxy moiety of 1 to 3 carbon atoms, X is a bond or straightor branched chain alkylene of 1 to 12 carbon atoms; and R ispyrrolidinyl, unsubstituted or substituted by one lower alkyl, carboxyor alkoxycarbonyl of 1 to 6 carbon atoms in the alkoxy moiety, or agroup of the formula --NH.R³, wherein R³ is pyrrolidinyl, unsubstitutedor substituted by one lower alkyl, carboxy or alkoxycarbonyl of 1 to 6carbon atoms in the alkoxyl moiety, to whole blood or platelet-richconcentrates.
 19. A pharmaceutical composition useful for the inhibitionof platelet aggregation and thrombus formation and for the treatment ofarterial thromboses in humans and animals which comprises a plateletaggregation inhibitory amount, an amount sufficient to inhibit theformation of thrombs or an anti-arterial thrombotically effective amountof a compound of the formula ##STR30## or a pharmaceutically acceptablenon-toxic acid addition salt thereof when there is a basic nitrogen atomin the molecule, wherein R¹ and R² are the same or different and each ishydrogen, lower alkyl, lower alkoxy, halo-lower alkyl, nitro, amino,acetylamino or halogen; or R¹ together with R² when attached to adjacentcarbon atoms form an alkylene moiety of 3 to 6 carbon atoms or anoxyalkyleneoxy moiety of 1 to 3 carbon atoms; X is a bond or a straightor branched chain alkylene of 1 to 12 carbon atoms; and pyrrolidinyl,unsubstituted or substituted by one lower alkyl, carboxy oralkoxycarbonyl of 1 to 6 carbon atoms in the alkoxyl moiety, or a groupof the formula --NH.R³ wherein R³ is pyrrolidinyl, unsubstituted orsubstituted by one lower alkyl, carboxy or alkoxycarbonyl of 1 to 6carbon atoms in the alkoxyl moiety, provided that when R¹ and R² are atpositions 5 and 7 and are hydrogen or halogen and X is lower alkylene,then R is not pyrrolidinyl which is attached via a nitrogen atom thereofto X; in combination with a pharmaceutically acceptable carrier providedthat R¹ and R² are not hydrogen or lower alkyl when x is alkylene of twocarbon atoms and R is unsubstituted pyrrolidinyl.